In the first phase of this project it was established, through data from social records, that men with an XYY chromosone complement, drawn from the general population, had an elevated crime rate which could be explained in part on the basis of their lower level of intellectual functioning. In the second phase, comprehensive individual case studies were conducted of groups of XYY and XXY men and their matched controls. The data from these studies will now be analyzed. The aims of the analyses to be done are: to determine whether these are distinctive XYY and XXY syndromes; to determine whether XXYs show more "feminine" characteristics and XXYs more "masculine" characteristics, including tendencies toward aggression; to determine whether, compared to normal XYs, XYYs and XXYs are at a high risk for cognitive dysfunctions and physical dysfunctions, suggesting that an extra sex chromosone has adverse effects on development; to examine the interrelated roles of social, developmental,and personality factors in contributing to differences between XYYs and (XXYs) who engage in criminal activity and those who do not.